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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package java.util;

/** {@collect.stats} 
 * {@description.open}
 * An iterator over a collection.  {@code Iterator} takes the place of
 * {@link Enumeration} in the Java Collections Framework.  Iterators
 * differ from enumerations in two ways:
 *
 * <ul>
 *      <li> Iterators allow the caller to remove elements from the
 *           underlying collection during the iteration with well-defined
 *           semantics.
 *      <li> Method names have been improved.
 * </ul>
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
 * Java Collections Framework</a>.
 * {@description.close}
 *
 * @author  Josh Bloch
 * @see Collection
 * @see ListIterator
 * @see Iterable
 * @since 1.2
 */
public interface Iterator<E> {
    /** {@collect.stats} 
     * {@description.open}
     * Returns {@code true} if the iteration has more elements.
     * (In other words, returns {@code true} if {@link #next} would
     * return an element rather than throwing an exception.)
     * {@description.close}
     *
     * @return {@code true} if the iteration has more elements
     */
    boolean hasNext();

    /** {@collect.stats} 
     * {@description.open}
     * Returns the next element in the iteration.
     * {@description.close}
     * {@property.open formal:java.util.Iterator_HasNext}
     * {@new.open}
     * In general, it is recommended to call hasNext() and check the return
     * value before calling this method.
     * {@new.close}
     * {@property.close}
     *
     * @return the next element in the iteration
     * @throws NoSuchElementException if the iteration has no more elements
     */
    E next();

    /** {@collect.stats} 
     * {@description.open}
     * Removes from the underlying collection the last element returned
     * by this iterator (optional operation).
     * {@description.close}
     * {@property.open formal:java.util.Iterator_RemoveOnce}
     * This method can be called
     * only once per call to {@link #next}.
     * {@new.open}
     * If the {@link #next} method has not yet been called, this method cannot be called.
     * {@new.close}
     * {@property.close}
     * {@property.open formal:java.util.Collection_UnsafeIterator formal:java.util.Map_UnsafeIterator}
     * The behavior of an iterator
     * is unspecified if the underlying collection is modified while the
     * iteration is in progress in any way other than by calling this
     * method.
     * {@property.close}
     *
     * @throws UnsupportedOperationException if the {@code remove}
     *         operation is not supported by this iterator
     *
     * @throws IllegalStateException if the {@code next} method has not
     *         yet been called, or the {@code remove} method has already
     *         been called after the last call to the {@code next}
     *         method
     */
    void remove();
}
